The interaction of E1 class of colicins with membranes will be investigated by various biochemical and biophysical means. The channel properties of colicin E1 will be studied in liposomal and bacterial membranes. Channel size and membrane specificity will be determined. Different functional domains on the protein will be identified by proteolitic and genetic modifications. New methods will be developed to study the kinetics and possible voltage-dependency of colicins in liposomes. These studies are expected to contribute to our understanding of the interaction of proteins with biological membranes as well as to our knowledge on the structure and functioning of membrane channels. The immunity mechanism by which colicinogenic cells are protected against colicin E1 will also be investigated. The immunity protein will be isolated and its molecular properties will be determined. The possibility of its interaction with colicin E1 will be explored. Temperature sensitive immunity mutants will be isolated and used to study the mode of action of the immunity protein.